>> david lee milner new york. thank you, david. american contractor working as an advisor with nato command in afghanistan was shot and killed today by afghan policewoman. the incident occurred outside police headquarters in kabul. the first known insider attack bay woman in afghanistan. >> as the faithful gather in bethlehem to usher in christmas, residents in syria praying for peace, if not on earth in their country. unfortunately, correspondent leland vittert tells us. that prayer doesn't look like it will be answered anytime soon. >> syrian rebels say the government tanks fired some type of poison gas on the city of homs. they uploaded victi videos, whee victims are shown receiving treatment. it shows they suffer from heavy dose of tear gas and irritant, no at chemical weapon like serrin gas. troops loyal to president bashar assad suddenly find themselves playing defense. force to abandon large swath of the north, they resorted to firing scud missiles in the direction of the rebel enclave. time and momentum appear on side of th